The present invention is directed to a blood flow cannula, and more particularly, to a generally rigid clampable blood flow cannula.
Cannulas are often used to guide blood flow out of a person's heart and into a ventricle assist device which aids the heart in delivering blood to the body. A first end of the cannula is passed directly through the heart wall, and is fixed in place by sewing a fabric cuff to the outer wall of the heart. A second end of the cannula is then coupled to a conduit which delivers the blood to the ventricle assist device. It is known to manufacture cannulas of clear polymer tubing. However, such cannulas are susceptible to kinking, or may be squeezed shut by internal organs abutting against the cannula, which blocks the flow of blood.
In response to this problem, cannulas were developed which had a coiled wire disposed inside the cannula. The coiled wire provides support to avoid kinking and collapsing of the cannula. However, it is often necessary to clamp the cannula to temporarily block the flow of blood therethrough. Cannulas having a coiled wire may be difficult to clamp, and/or may not have sufficient resiliency to return to their original unclamped shape once the clamp is removed. Accordingly, there exists a need for a cannula which avoids kinking and inadvertent closure, but can be clamped and return to its original position when the clamp is removed.